Protein is only used as a respiratory substrate when an individual is suffering from starvation, when all carbohydrate and lipid stores have been used up.
Tissue protein becomes mobilised to allow it to be used for energy supply. Protein is hydrolysed (by protease) into its amino acids.
The amino acids are the deaminated in the liver, the amino group is converted into urea and is excreted. The residue is converted to a Krebs cycle intermediate (pyruvate, acetyl CoA etc.).
Acetyl CoA is like a crossroads in metabolism, it is formed during oxidation of carbohydrates, lipids and proteins, allowing all substrates to be fed into the krebs cycle at the same point.
Comments
No comments have yet been made